Chromosome 10 contains genes encoding, for example, the alpha-2A-adrenergic receptor, the beta-1-adrenergic receptor, glyceryl-3-phosphate acyltransferase and G protein-coupled receptor kinase-5. Recently, it has been shown that the soluble (cytosolic) aminopeptidase P gene (XPNPEP1) is disposed at 10q25.3 (Sprinkle et al. Arch. Biochem. Biophys. 378: 51–6, 2000), a gene discussed in further detail below.
Human Soluble Aminopeptidase P
Human soluble aminopeptidase P, an aminoacylprolyl peptidyl hydrolase, catalyzes the removal of the N-terminal amino acid from peptides in which the second residue is proline. It is believed to act physiologically by degrading peptide hormones such as bradykinin and substance P. It may also degrade collagen-related peptides that have N-terminal sequences of the type Xaa-Pro-Hyp-. A functionally-related enzyme is membrane-bound aminopeptidase P, the gene for which (XPNPEP2) is disposed at chromosome Xq25 (Sprinkle et al, Genomics 50: 114–6, 1998). The membrane-bound enzyme is disposed, via a glycosylphosphatidylinositol lipid anchor, as an ectoenzyme on endothelia and epithelia. Soluble aminopeptidase P is disposed intracellularly in virtually all cell types, including astrocytes, lymphocytes, platelets and chromaffin cells.